Explosionproof switch housing



March 26, 1940. c. A. HARDAGE 2,194,549

EXPLOSIONPROOF SWITCH HOUSING Filed April 3. 1939 INVENTOR. CLARENCE A.HARD/46E- WWW AT ORNEYS.

Patented Mar. 26, 1940 UNITED STATES PATENT OFFICE Grouse-Hinds Company,Syracuse, N

poratlon of New York .Ysacot- Application April 3, 1939, Serial No.265,716

8 Claims.

This invention relates generally to explosionproof switch housings ofthe type disclosed in my Patent No. 2,156,564 of May 2, 1939, whichcomprises a main body section provided with one or 6 more internallythreaded openings into each of which an end closure is threaded.

More particularly this invention has as an object an explosionproofswitch housing of the type referred to embodying a structure operable toprevent removal of one or both of the end closures while the switch orcircuit breaker arranged in the housing is in the on position, and whichstructure is particularly economical to construct, efficient inoperation, and which may be conveniently manipulated.

The invention consists in the novel features and in the combinations andconstructions hereinafter set forth and claimed.

In describing this invention, reference is had so to the accompanyingdrawing in which like characters designate corresponding parts in allthe views.

Figure 1 is a front elevational view of an explosionproof switch housingembodying my inven- 25 tion.

Figure 2 is a side elevational view of the device shown in Figure 1 withparts broken away and parts in section.

Figure 3 is a fragmentary view of .the left-hand portion of Figure 2illustrating the end closure interlock in released position.

Figure 4 is a detached view of the interlocking bar.

The explosionproof switch housing, to which the present embodiment of myinvention is applied, consists of a body section III of substantiallycylindrical form provided with one or more bosses Ii having conduitreceiving apertures at l2. Each side of the body section Ill is providedwith an internally threaded opening IS in which is threaded an endclosure it. It will be understood that the openings II are substantiallycoextensive with the body and form a sizable opening to permitinstallation, repair, or removal of the switch or other electricalapparatus mounted within the housing. The end closures H are of generaltubular construction and may be of any suitable length to house theparticular apparatus mounted in the housing.

As here shown, the end closures are provided with transversely extendingslots I! at their outer ends for the reception of a piece of pipe orother implement to aid in threading and unthreading the end closures tothe body section III. A shaft I8 is iournalled in one side of thehousing H), the

inner end being connected to the switch or circuit breaker, and theouter end being provided with an operating handle I! which is here shownas being provided, intermediate its ends, with transversely extendingprojections carrying the on and of! legends. In Figure 1, the handle I!is shown in full line in the of! position, and in dotted outline in theon position. Preferably, the side of the body section, on which theswitch operating handle is mounted, is formed with a rectangu- 19 larshaped flat surface 2i and a pad or plate 22 is secured to the bodysection by screws 23 and is maintained in spaced apart relation theretoby spacing collars 24 mounted upon the fastening screws. The plate 22 isprovided with one or 15 more apertures 25 for the reception of a padlockto secure the handle in either the off or on positions.

Enclosed explosionproof fittings of the type herein referred to are usedto house electrical 20 apparatus in locations where the surroundingatmosphere contains explosive substances. Any explosive mixture withinthe housing may become ignited with the arcing of the contacts of theswitch when the same are opened or closed, and 25 the purpose of such ahousing is to prevent the escape of the ignited gases to the surroundingatmosphere. In order to maintain a maximum condition of safety, it isdesirable that the closures of the housing be not removed while theswitch is in the on position and to also prevent movement of the switchto the on position after the closure has been removed, or at leastduring removal of the closure.

The structure herein employed to accomplish 5 this purpose consists of abar 30 slidably mounted on the body section III and being arranged to bemoved into and out of engagement with the end closure or, as here shown,into and out of engagement with both of the end closures l4 and beingoperable, when in engagement with the end closures, to prevent the samefrom being unthreaded from the body section 12.

The bar 30 is formed with an elongated slot 3| intermediate its ends,the slot having an enlarged portion at 32. The bar 30 is arrangedintermediate the flat surface 2| of the body section and the plate 22,the width of the slot 3| being such as to permit the bar to be slidablymounted on the spacing collars 24. The end closures are provided withone or more projections 33, and the ends of the bar 20 extend inwardlyso as to engage with the projections 33 upon rotation of the endclosures.

In the structure illustrated, the bar 30 engages ,the projections 38 onboth of the end closures I4,

and the slot 3| is of sufilcient length to permit the bar to be movedaxially a suiilcient distance to clear the projections on both of theend closures. The bar 30 is held in central position engaging both endclosures by a screw 35 threaded into the wall of the body section ID.The shank of the screw is slightly less in diameter than the width ofthe slot 3|, whereby the bar 30 may be moved axially when the screw isthreaded outwardly, as illustrated -in Figure 3. The head of the screwis substantially coextensive with the enlarged portion 32 of the slotand when the screw is threaded inwardly, as illustrated in Figure 2,with the head of the screw arranged in the enlarged portion of the slot,axial movement of the bar 30 is prevented. The arrangement or locationof the screw 35 is such that the head of the screw is covered by theswitch handle is when the handle is moved to the on position. That is,the handle is operable in the on position to prevent access to the screw35. g

When the handle I9 is moved to the off position, the screw may be backedout until the head portion thereof clears the bar 30. Thereupon, the barmay be moved axially out of engagement with the end closures H, asillustrated in Figure 3. The switch handle I9 however can not then bemoved into the on position because of the projecting head of the screw35. After the bar 30 has been shifted out of engagement with the endclosures I, it may be secured in shifted position upon tightening thescrews 35 bringing the head of the screw into engagement with the bar,as illustrated in Figure 3.

When in operative position, the bar 30 positively prevents unthreadingof the end closures M from the body section. The structure described isparticularly simple requiring only the addition of the bar 30 and thescrew 35 to the fitting, with the result that while the structure ishighly efllcient for the purpose intended, it does not add anyappreciable cost to the fitting.

What I claim is:

1. An explosionproof switch housing comprising a body section providedwith a conduit receiving aperture and a threaded opening in one side, aclosure threaded into said opening, a bar slidably mounted on the bodysection and shiftable into and out of engagement with said closure andbeing operable when in engagement with the closure to prevent the samebeing unthreaded from the opening, means coacting with said bar and bodysection to retain said bar in engagement with said closure and beingoperable to release said bar, a switch operating handle mounted on thebody section and being movable into on and off positions and beingoperable, when in on position, to prevent operation of said means, saidmeans being operable when said switch handle is in oil position torelease said bar to permit the same to be shifted out of engagement withsaid closure.

2. An explosionproof switch housing comprising a body section providedwith a conduit receiving aperture and a threaded opening in one side, aclosure threaded into said opening, a bar slidably mounted on the bodysection and shiftable into and out of engagement with said closure andbeing operable when in engagement with the closure to prevent the samebeing unthreaded from the opening, means coacting with said bar and bodysection to retain said bar in engagement with said closure and beingoperable to release said bar, a switch operating handle mounted on thebody section and being movable into on and oil positions and beingoperable, when in on position, to prevent operation 01' said means, saidmeans being operable when said switch handle is in oil position torelease said bar to permit the same to be shifted out of engagement withsaid closure and to prevent movement of the switch handle into the onposition.

3. An explosionproof switch housing comprising a body section providedwith a conduit receiving aperture and a threaded opening, a closurethreaded into said opening, a bar slidably mounted upon the body andbeing shittable into and out of engagement with said closure and beingoperable when in engagement with said closure to prevent the same beingunthreaded from said opening, a screw threaded into said body sectionand engaging said bar to retain the same in engagement with saidclosure, a switch handle pivotally mounted on said body section andbeing movable into on and oil positions, said switch handle beingarranged to prevent said screw from being threaded outwardly when saidhandle is in the on position, and said screw being operable whenthreaded outwardly to release said bar and to prevent movement of theswitch handle into the on position.

4. An explosionproof switch housing comprising a body section providedwith a conduit receiving aperture and a threaded opening, a closurethreaded into said opening, a screw having a threaded shank and anenlarged head portion, a bar mounted on said body section and beingformed with an elongated slot to receive the shank of said screw, andbeing slidable into and out of engagement with said closure and beingoperable when in engagement with said closure to prevent the same beingunthreaded from said opening, said slot having an enlarged portion toreceive the head of the screw when the latter is threaded inwardly toretain said bar from sliding movement and to hold the same in engagementwith said closure, a switch operating handle mounted on the body sectionand being movable into on position when said screw is threaded inwardlywith the head thereof arranged in the enlarged portion of said slot, andsaid screw being operable when threaded outwardly to prevent movement ofthe switch handle into the on position.

5. An explosionproof switch housing comprising a body section providedwith a conduit receiving aperture and a threaded opening, a closurethreaded into said opening, a screw having a threaded shank and a headportion, a bar slidably mounted upon the body section and beingshiftable into and out of engagement with said closure and beingoperable when in engagement with said closure to prevent the same beingunthreaded from said opening, said bar being formed with an elongatedslot to receive the shank of said screw when the same is threaded intothe body section and said slot having an enlarged arranged when in onposition to prevent said screw from being threaded outwardly, and saidscrew being operable when threaded outwardly to prevent movement of theswitch handle into the on position.

6. An explosionproot switch housing comprising a body section providedwith a conduit receiving passage and having a threaded opening at eachend, an end closure threaded into each of said openings and having aprojection extending radially therefrom, a bar mounted on the body andextending axially thereof, said bar being formed with a slot extendinglengthwise thereof and having an enlarged portion intermediate its ends,a screw extending through said slot and being threaded into the body andhaving a head portion of greater width than said slot, said enlargedportion of the slot being arranged to receive the head of the screw withthe ends or the bar positioned to engage the projections on the endclosures respectively to prevent the same being unthreaded from thebody, a switch operating handle pivotally mounted on the body and beingoperable when in the on position to prevent said screw being unthreadedto move the head thereof out of the enlarged portion of said slot, andsaid screw and switch operating handle being arranged relatively wherebysaid screw prevents movement of the switch handle into the on positionwhen the head of the screw is moved out. of said slot.

CLARENCE A. HARDAGE.

